The present invention relates generally to a heating and cooling system, and more particularly to a fuel fired heating and cooling system which is energy efficient on both the cooling mode of operation and the heating mode of operation.
A variety of heat powered heating and cooling systems for buildings has been provided by the prior art. Such systems typically include a vapor power circuit such as a steam power circuit having a prime mover expander such as a turbine. The prime mover expander drives a compressor within a refrigeration circuit which is used as a reversible heat pump for heating and cooling the building.
One such prior art system, as shown in U.S. Pat. No. 3,400,554, utilizes the rejected heat from the vapor power circuit prime mover expander to supplement the heat furnished by the reversible refrigeration circuit when the system is on the heating mode. Another prior art system, as shown in U.S. Pat. No. 3,487,655 utilizes the prime mover expander to drive an alternator which provides electrical power for an electric motor driven compressor and for the associated electric motor driven heat pump fans.
The present invention departs from these and other prior art air heating and cooling systems by providing an air heating and cooling system having series heat exchange for the refrigeration and vapor power circuits both inside the building and outside the building. The system includes an expansion type refrigeration circuit having a compressor, an indoor heat exchanger, and an outdoor heat exchanger. The system also includes a closed vapor power circuit having a vapor generator including a boiler and a superheater, a prime mover expander such as a turbine, an indoor heat exchanger, and an outdoor heat exchanger.
The two series indoor heat exchangers and the two series outdoor heat exchangers are arranged with the refrigeration circuit heat exchangers upstream in the air flow path of the vapor power circuit heat exchangers. A first fan arrangement conducts air across the indoor heat exchangers, and a second fan arrangement conducts air across the outdoor heat exchangers.
When the system is in a heating mode of operation, the indoor refrigeration circuit heat exchanger serves as a condenser to provide one stage of heating for the indoor air, and the indoor vapor power circuit heat exchanger receives the outlet vapor from the prime mover expander to provide a second stage of heating for the indoor air. The outdoor heat exchanger of the vapor power circuit does not receive outlet vapor from the prime mover expander during the heating mode.
When the system is on the cooling mode of operation, the indoor refrigeration circuit heat exchanger serves as an evaporator to cool the indoor air, and outlet vapor from the prime mover expander is directed away from the indoor vapor power circuit heat exchanger. The outdoor refrigeration circuit heat exchanger functions as a condenser, and the outlet vapor from the prime mover expander is conveyed to the outdoor vapor power circuit heat exchanger during the cooling mode.
The prime mover expander also drives an alternator which provides electrical power to the first and second fan arrangements. As the speed of the prime mover expander is increased, the electrical power output of the alternator increases to increase the speed of the fans and thereby increase air flow across both the indoor and outdoor heat exchangers. During very cold weather, vapor from the vapor generator is incrementally injected directly into the indoor vapor power circuit heat exchanger to increase the heating capacity of the system and avoid undesirable compressor operating conditions.
The entire system is assembled in a common housing, and a first insulating wall in the housing thermally insulates the vapor generator and the prime mover expander and the refrigerant compressor from the heat exchangers. A second insulating wall in the housing thermally insulates the series indoor heat exchangers from the series outdoor heat exchangers.
Although the system is described herein with reference to indoor and outdoor air, the system can also be used with indoor and outdoor fluids other than air such as water or brine. Additionally, the indoor and outdoor fluids need not be the same fluid, for example when the indoor fluid is air and the outdoor fluid is ocean brine.